Old Lady Cactus
Mammillaria hahniana
Also known as: Old Lady Cactus, Birthday Cake Cactus, Powder Puff Cactus
Cactaceae
Last reviewed: June 2026 · Source: ASPCA Animal Poison Control
A distinctive cactus covered in long, silky white hairs and fine spines, giving it a fluffy, snow-covered appearance. Produces a ring of vivid purple-pink flowers.
Toxicity
Source: ASPCA Animal Poison Control Center. Always consult a veterinarian if your pet ingests any plant.
Care Guide
Pot Size
Frequently Asked Questions
Is Old Lady Cactus toxic to cats?↓
No, Old Lady Cactus is not toxic to cats and is considered pet-safe according to the ASPCA. It is generally safe to keep in homes with cats.
Is Old Lady Cactus toxic to dogs?↓
No, Old Lady Cactus is not toxic to dogs. It is listed as non-toxic by the ASPCA and is safe to have around dogs.
How often should I water Old Lady Cactus?↓
Water Old Lady Cactus every 14–21 days. Allow the soil to dry out completely between waterings — this plant is drought-tolerant and prone to root rot if overwatered.
How much light does Old Lady Cactus need?↓
Old Lady Cactus thrives in direct sunlight, ideally a south- or west-facing window. It is forgiving and adapts to a range of light conditions.
What size pot does Old Lady Cactus need?↓
Use a pot between 4″ and 8″ in diameter. When repotting, choose a pot only 1–2″ larger than the current one — too much space retains excess moisture and can lead to root rot.